1. Field of the Invention
The present invention is directed to the preparation of high purity barium sulfate, and, more particularly, to a novel, solid-state, low-temperature process for the preparation thereof.
2. Description of Related Art
Barium sulfate (BaSO.sub.4) ceramic is a superlative optical reflector, and may soon become a viable component of optical circuits.
Precipitation is presently a favored method of preparation of BaSO.sub.4 because of its low solubility: at 18.degree. C., 100 g of water dissolves 0.002 g BaSO.sub.4. A high-purity product is difficult to obtain by precipitation, however, because the BaSO.sub.4 precipitate is a notorious carrier for dragging down dissolved impurities. These impurities serve as centers of, or sources for, radiation damage, a behavior that limits severely the application of the derived ceramic ware as an optical reflector for high-power applications.
As found in nature, the mineral (heavy spar) is not sufficiently pure. It should be colorless, but the presence of impurities impart a color. Again, the manufactured ceramic for IR-UV reflectors is prone to radiation damage (coloring) when the BaSO.sub.4 is impure.
A method for the preparation of high purity barium sulfate is required.